1. Field of the Invention
The present invention relates to a pull-out type air circuit breaker with a main body which can be pushed in or pulled out on a cradle, and particularly, to an automatic discharging apparatus for a closing spring in an air circuit breaker in which the closing spring is allowed to be automatically discharged while pulling out the main body of the air circuit breaker, and also the closing spring is prevented from being charged due to operating of a closing spring charging handle in a state that the main body has completely been pulled out.
2. Background of the Invention
In general, an air circuit breaker is an electronic device which selectively opens or closes an electric circuit between a power source side and a load side in the air. The air circuit breaker may be classified into a fixed type air circuit breaker fixedly connected to circuit connection terminals of the respective power source side and load side, and a pull-out type air circuit breaker having its main body allowed to be pushed in or pulled out of a cradle with circuit connection terminals of respective power source side and load side. In the recent time, due to the difficulty of maintenance of the fixed type air circuit breaker, the pull-out type air circuit breaker are broadly used.
As defined in standards of electric devices, such pull-out type air circuit breaker should employ a pull-out interlocking device for safely protecting an operator or a repair inspector from risks which may be caused due to an accidental discharging of an energy storage device (e.g., a spring charging device).
Therefore, the present invention was invented as such pull-out interlocking device.
Now, an operation of pushing in and pulling out a general pull-out type air circuit breaker and an electrical operation accordingly performed will be briefly described with reference to FIGS. 1A to 1D.
FIG. 1A is a state view showing a connection position of a general pull-out type air circuit breaker. In the state as shown in FIG. 1A, a main circuit terminal C2 of a cradle and main circuit terminals 20b of a main body 20 of the air circuit breaker are electrically connected to each other such that a power source side and a load side of the main circuit can be in an electrically connected state via the air circuit breaker.
Referring to FIG. 1A, reference numeral 20a denotes the control signal receiving terminal of the main body 20 to receive a switching control signal of the air circuit breaker, C1 denotes the cradle control signal terminal to transfer the switching control signal received from the exterior to the control signal receiving terminal 20a, numeral 1 denotes a switching mechanism of the air circuit breaker, and H1 designates a closing spring charging handle. The state in FIG. 1A corresponds to the main circuit and the control signal receiving terminal 20a being connected to each other, namely, a so-called connected position.
FIG. 1B is a state view showing that the main circuit is broken by the main circuit terminal 20b being disconnected and the control circuit terminal 20a being connected in the general pull-out type air circuit breaker. This state corresponds to a state at the beginning of pulling out the pull-out air circuit breaker. In this state, the main circuit terminal C2 of the cradle is disconnected from the main circuit terminals 20b of the main body 20 of the air circuit breaker such that the power source side and the load side of the main circuit are electrically broken. Also, the state shown in FIG. 1B corresponds to a test position at which a switching operation can be tested by sending only the switching control signal to the air circuit breaker under the main circuit being broken.
FIG. 1C is a state view showing that nor the main circuit terminal 20b and the control circuit terminal 20a are connected in the general pull-out type air circuit breaker. Here, the state is referred to as a disconnected position that the pull-out type air circuit breaker is disconnected from both the main circuit and the control circuit.
FIG. 1D is a state view showing that the main body 20 of an air circuit breaker is pulled out of the cradle C along pull-out rails in the general pull-out type air circuit breaker. Here, this state is referred to as a pulled-out position at which nor the main circuit terminal 20b and the control circuit terminal 20a are disconnected and the air circuit breaker is completely pulled out of the cradle C for maintenance.
FIGS. 2 to 5 are views showing a relation between a cam shaft and a closing spring in charging and discharging in a related art air circuit breaker with an automatic discharging device for the closing spring. FIG. 2 is a cross-sectional view showing a switching mechanism in a state that the air circuit breaker is broken. FIG. 3 is a cross-sectional view showing the switching mechanism of the air circuit breaker according to the related art, which shows a charged state of the closing spring. FIG. 4 is a cross-sectional view showing the switching mechanism of the air circuit breaker according to the related art, which shows a state of the switching mechanism being closed due to discharging of the closing spring. FIG. 5 is a perspective view showing the switching mechanism of the air circuit breaker according to the related art.
Configuration and operation of the switching mechanism of the related art air circuit breaker will be described with reference to FIGS. 2 to 5.
First, the configuration of the switching mechanism in the related art air circuit breaker will be described with reference to FIGS. 2 to 5.
As shown in FIG. 2, the switching mechanism of the air circuit breaker includes a stationary contactor 12, and a movable contactor 11 connected to the stationary contactor 12 to be movable to a closing position at which a conduction circuit is closed, and disconnected from the stationary contactor 12 to be movable to a breaking (trip) position at which the conduction circuit is opened.
Still referring to FIG. 2, the movable contactor 11 is connected to a main shaft lever 10-1 to be in contact with the stationary contactor 12 or separated from the stationary contactor 12 according to a rotational direction of the main shaft lever 10-1.
The main shaft lever 10-1 is typically used when the air circuit breaker opens or closes each of conducting paths for 3 phases. Thus, three of the main shaft levers 10-1 are required in total (i.e., one for each phase). Each main shaft lever 10-1 drives the movable contactor 11 for the corresponding phase.
In order for the three main shaft levers 10-1 to be simultaneously driven, each of the main shaft levers 10-1 is coaxially connected to one common main shaft 10.
Therefore, the main shaft 10 penetrates both side plates 1 supporting the switching mechanism 1 so as to extend to be connected to the main shaft lever 10-1 of a different phase.
Among the three main shaft levers 10-1, the central main shaft lever 10-1 connected to the switching mechanism 1 has one end portion connected to the main shaft 10 and another end portion connected to a first link 6.
Like gears having different pivots and engaged with each other, one end portion of the first link 6 is connected to the main shaft lever 10-1, such that the main shaft lever 10-1 and the first link 6 are rotated in mutually opposite directions. The first link 6 provides a driving force to the central main shaft lever 10-1 among the three main shaft levers, to allow the central main shaft lever 10-1 to drive the movable contactor 11 to an opening or closing position.
A second link 4 is connected to another end portion of the first link 6, and the first and second links 6 and 4 are rotated in the same direction.
A third link 3 is rotatably disposed, which has one end portion connected to another end portion of the second link 4 by a driving connection pin P, so as to transfer the driving force to the second link 4.
A closing spring unit includes a closing spring 13 which provides a driving force to drive the movable contactor 11 to the closing position, and a closing spring seat (no reference numeral given). The closing spring 13 charges elastic energy, and then discharges the charged elastic energy to provide a driving force to allow the movable contactor 11 to be moved to the closing position.
In order to avoid the release of the closing spring 13 and support the rotation of the closing spring seat, a closing spring support bracket 18 is employed which supports another end of the closing spring 13 opposite to the one end of the closing spring 13 from which the driving force of the closing spring is provided.
The switching mechanism 1 of the air circuit breaker includes a charging cam 2 which provides a driving force for charging an elastic force of the closing spring unit. The charging cam 2 is rotatable together with a cam shaft 2a. The charging cam 2 is provided with a cam roller 2b represented by a dotted line in FIG. 5 on one side of a rear surface thereof.
The third link 3 is coaxially connected to the cam shaft 2a of the charging cam 2 to be rotatable together.
Referring to FIG. 5, a driving lever 16 includes a driving lever pin 16b which is in contact with the second link 4 to allow the second link 4 to be driven. The driving lever 16 is implemented as a pair (i.e., 16 and 16) spaced apart from each other by the driving lever pin 16b, and the second and third links 4 and 3 are interposed between the pair of levers 16. The driving levers 16 are connected to the closing spring unit, such that it can supply a driving force for charging elastic energy to the closing spring unit or can be rotatable upon receiving the discharged elastic energy from the closing spring unit.
As shown in FIG. 2, an opening spring 14 is a spring having one end supported by the main shaft lever 10-1 and another end supported by a spring support pin (no reference numeral given) fixed onto the side plate 1. The opening spring 14 is tensioned by a clockwise rotation of the main shaft lever 10-1 at the time of a closing operation so as to charge elastic energy. The opening spring 14 then discharges the charged elastic energy at the time of breaking a circuit to provide a driving force such that the main shaft lever 10-1 can be rotated in a counterclockwise direction.
As shown in FIG. 5, a pair of third link elastic bias springs 15 are provided. Each third link elastic bias spring 15 has one end supported by a driving lever pin 16b of the driving levers 16 and another end supported by a driving connection pin P which allows the second and third links 4 and 3 to be driven.
The driving connection pin P penetrates the second and third links 4 and 3 to allow the second and third links 4 and 3 to be driven. The driving connection pin P extends to be protruded such that the pair of third link elastic bias springs 15 can be supported at its both ends.
In order to avoid interference by the protruded driving connection pin P, the pair of driving levers 16 and 16 are spaced apart from each other by a predetermined distance.
A closing latch 5 extends in a vertical direction so as to have one surface located on a moving locus of the can roller 2b disposed at one surface of the charging cam 2. Accordingly, the closing latch 5 can latch the rotation of the charging cam 2. An upper end portion of the closing latch 5 is located on a rotating path of an on-shaft 8. Thus, the closing latch 5 may be latched or released by the on-shaft 8.
The on-shaft 8 is connected to an on-button (not shown) to be manually rotated or automatically rotated by being connected to an electrical driving controller and an actuator.
A recess 3a is formed at an upper portion of the third link 3. An opening latch roller 7a is disposed which is movable to a position at which it can enter the recess 3a of the third link 3 or separated therefrom. Also, an opening latch 7 rotatable centering around a pivot 7b thereof is disposed above the third link 3. One end portion of the opening latch 7 is connected to an opening latching spring 7c by a pin. Accordingly, the opening latch 7 receives an elastic bias force applied from the opening latch spring 7c such that is can be allowed to be rotated counterclockwise in FIGS. 2 to 4.
An off-lever 9 is disposed to be in contact with another end of the opening latch 7 in a length direction. The off-lever 9 latches or releases the rotation of the opening latch 7.
Operations of the switching mechanism of the related art air circuit breaker having such configuration are divided into a charging (elastic force charging) operation, a closing operation and an opening (breaking) operation, which will now be described.
First, the charging operation of the closing spring is described with reference to FIG. 3.
The cam shaft 2a of the charging cam 2 is rotated by the closing spring charging handle (not shown) or a driving motor (not shown) in a counterclockwise direction based on the drawing.
Accordingly, as a radius of curvature at the outer circumferential surface of the charging cam 2 is reduced, the driving lever roller 16a of the driving lever 16 being in contact with an outer circumferential surface of the charging cam 2 is compressed. The driving lever roller 16a then presses the spring seat of the closing spring unit which is contacted to be pressed by the driving lever roller 16a, thereby compressing the closing spring 13.
Here, as the charging cam 2 is rotated, the driving lever roller 16a rolls along the outer circumferential surface of the cam 2. The charging cam 2 is rotated until the cam roller 2b disposed at one surface thereof is in contact with the closing latch 5.
With respect to the counterclockwise rotation of the charging cam 2, the third link 3, the second link 4 and the driving lever 16 interwork together to thusly be rotated in the counterclockwise direction.
Here, the rotation of the main shaft 10 is latched by the opening latch 7. Accordingly, the movable contactor 11 is kept separated from the stationary contactor 12 as shown in FIG. 3.
As the third link 3 is rotated in the counterclockwise direction, the latch roller 7a of the opening latch 7 is received into the recess 3a of the third link 3 so as to latch the counterclockwise rotation of the third link 3.
The cam roller 2b disposed at one surface of the charging cam 2 is in contact with the closing latch 5, thereby pushing the closing latch 5. The closing latch 5 is then rotated in the clockwise direction centering around its pivot. The clockwise rotation of the closing latch 5 is restrained by the on-shaft 8, resulting in completing the charging operation of the closing spring 13.
On the other hand, the closing operation of the switching mechanism of the related art air circuit breaker will now be described with reference to FIG. 4.
When the on-shaft 8 is manually rotated or automatically rotated by being connected to an electrical driving controller and an actuator via the on-button (not shown), the closing latch 5 is released from the On-shaft 8 to be rotated in the clockwise direction.
As the closing latch 5 is released, the cam roller 2b is also released from the closing latch 5.
Accordingly, the driving lever roller 16a, which has restrained discharging of the closing spring 13 while being in contact with the outer circumferential surface of the charging cam 2, diverges from the outer circumferential surface of the charging cam 2.
As the closing spring 13 is discharged, the driving lever 16 is pressed by the spring seat of the closing spring 13 to be rotated in the counterclockwise direction. Accordingly, the driving lever pin 16b pushes the second link 4 to rotate it in the counterclockwise direction on the drawing. The counterclockwise rotation of the second link 4 rotates the third link 3 in the counterclockwise direction. Therefore, the first link 6 is pressed to be pushed up by the second link 4, so as to be rotated in the counterclockwise direction.
The main shaft lever 10-1 and the first link 6 are connected to each other for interlocking. Accordingly, according to the counterclockwise rotation of the first link 6, the main shaft lever 10-1 is rotated in the clockwise direction by interworking with the first link 6, and simultaneously the main shaft 10 is rotated in the clockwise direction. Therefore, the movable contactor 11 interworking with the main shaft lever 10-1 is rotated in the counterclockwise direction on the drawing to be in contact with the stationary contactor 12, thereby closing the conduction circuit.
Here, the breaking spring 14 is in a tensioned state, namely, a state of charging (i.e., accumulating, storing) elastic energy.
Now, the opening operation of the switching mechanism in the related art air circuit breaker will be described with reference to FIG. 2.
When the off-shaft 9 is manually rotated clockwise or automatically rotated clockwise by being connected to an electrical driving controller and an actuator via the off-button (not shown), the opening latch 7 is released from the off-shaft 9 and rotated in the clockwise direction by the elastic force of the opening latch spring 7c. Also, the opening latch 7 is released from the recess 3a of the third link 3.
As the third link 3 is released from the opening latch 7, the interworked second and first links 4 and 6 are also released. Also, in a state that the opening spring 14 is tensioned while the closing operation, a support end portion of its main shaft lever 10-1 is returned to the side of the spring support pin of the side plate 1, and accordingly, the breaking spring 14 discharges the charged elastic energy, thereby rotating the main shaft lever 10-1 in the counterclockwise direction. Accordingly, the movable contactor 11 is rotated in the clockwise direction to be separated from the stationary contactor 12. Therefore, the conduction circuit is opened.
Such configured air circuit breaker may be pulled out in the state of the closing spring being charged without any means for discharging the elastic energy of the closing spring, when the closing spring is charged while the air circuit breaker main body is pulled out of the cradle.
When the closing spring is moved to the pulled-out position from the charged state, if the on-button is pressed by a user's mistake, the closing spring is discharged such that the air circuit breaker main body performs the closing operation. Here, the user may be surprised to hear sound occurred during the closing operation or any collateral accident may be caused.
Also, under the state that the main body of the air circuit breaker is pulled out of the cradle, the user may charge the closing spring by using the closing spring charging handle, which may resulting in an unstable state of the main body of the air circuit breaker due to the charged elastic energy.